Scores of firefighters were staging in Nanakuli Valley on Saturday night to monitor an uncontrolled wildfire that was burning toward homes and could force residents to evacuate overnight.

Honolulu Fire Department Capt. James Todd said the fire was still about a half-mile from homes around Haleakala Avenue about 7 p.m., but windy conditions could push the flames dangerously close to homes overnight. He said about 80 firefighters were staging around the neighborhood to safeguard property.

About 50 firefighters battled the blaze throughout the day Saturday, but it was still uncontained and had grown to about 1,500 acres, Todd said. Steep terrain and high winds that were fanning the flames hampered firefighting efforts.

Firefighters cut fire breaks with hand tools near the ridgeline and others extinguished the flames toward the base of the mountain. Three helicopters — two from the state Department of Forestry and Wildlife and one from HFD — made water drops during the day.

The fire erupted about 6 p.m. Thursday near Pikaiolena Street and Waiea Place on the Ko Olina side of the valley.

Responding firefighters found a 2-acre fire slowly moving downslope toward homes in Nanakuli Valley and staged around Pikaiolena Street to protect the homes. About 8:30 that night, police closed the roads and notified residents of a voluntary evacuation. Residents were allowed back into their homes about 10:30 p.m.

Firefighters contained the fire Friday morning when it was about 400 acres in size. But later that morning, it flared up again and, by Friday night, had grown to about 1,000 acres and was moving away from structures.

Todd said Saturday evening that the fire was now approaching the homes on the opposite side of the valley as it did the night it started.